package pfile

import (
	"bytes"
	crand "crypto/rand"
	"math/rand"
	"testing"

	"git.crumpington.com/public/jldb/lib/errs"
)

func randomPage(t *testing.T) dataPage {
	p := newDataPage()
	h := p.Header()

	x := rand.Float32()
	if x > 0.66 {
		h.PageType = pageTypeFree
		h.DataSize = 0
	} else if x < 0.33 {
		h.PageType = pageTypeHead
		h.DataSize = rand.Uint64()
	} else {
		h.PageType = pageTypeData
		h.DataSize = rand.Uint64()
	}

	h.CollectionID = rand.Uint64()
	h.ItemID = rand.Uint64()

	dataSize := h.DataSize
	if h.DataSize > pageDataSize {
		dataSize = pageDataSize
	}

	if _, err := crand.Read(p.Data()[:dataSize]); err != nil {
		t.Fatal(err)
	}

	h.CRC = p.ComputeCRC()

	return p
}

// ----------------------------------------------------------------------------

func TestPageValidate(t *testing.T) {
	for i := 0; i < 100; i++ {
		p := randomPage(t)

		// Should be valid initially.
		if err := p.Validate(); err != nil {
			t.Fatal(err)
		}

		for i := 0; i < pageSize; i++ {
			p[i]++
			if err := p.Validate(); !errs.Corrupt.Is(err) {
				t.Fatal(err)
			}
			p[i]--
		}

		// Should be valid initially.
		if err := p.Validate(); err != nil {
			t.Fatal(err)
		}
	}
}

func TestPageEmptyIsValid(t *testing.T) {
	if err := emptyPage.Validate(); err != nil {
		t.Fatal(err)
	}
}

func TestPageWrite(t *testing.T) {
	for i := 0; i < 100; i++ {
		page := newDataPage()
		h := page.Header()
		h.PageType = pageTypeData
		h.CollectionID = rand.Uint64()
		h.ItemID = rand.Uint64()
		h.DataSize = uint64(1 + rand.Int63n(2*pageDataSize))

		data := make([]byte, h.DataSize)
		crand.Read(data)

		n := page.Write(data)
		h.CRC = page.ComputeCRC()

		if n > pageDataSize || n < 1 {
			t.Fatal(n)
		}

		if !bytes.Equal(data[:n], page.Data()[:n]) {
			t.Fatal(data[:n], page.Data()[:n])
		}

		if err := page.Validate(); err != nil {
			t.Fatal(err)
		}
	}
}